feat: choose a group for quick favorites

[josexy]

Summary

• add a reusable favorite group picker for quick favorite actions
• default each open to the Default group and support inline group creation
• use all-group favorite indexing across the server list, history, detail panel, and detail window
• keep filled favorite icons as cancel actions and preserve other group memberships
• add English and Simplified Chinese UI copy

Why

Quick favorite buttons previously saved directly to the Default group, so users could not choose where a server belonged without editing it afterward.

User impact

Empty favorite icons now open a lightweight group picker. Users can choose an existing group or create and select a new one before explicitly saving. Existing favorite removal behavior remains available from filled icons.

Validation

• npm run build
• git diff --check
• Tauri development smoke test for dialog opening, Default selection, inline creation UI, and cancel-without-save behavior